Agonizing over whether to let them in suggests they have let in other questionable entities. "Fairness" is a smokescreen. Nobody honest needs a certificate from a dodgy authority, and nobody with a certificate from a dodgy authority deserves benefit of doubt.
there are some standards which companies have to comply with in order to be considered a "trustworthy" provider (e.g. for CA's)
https://www.etsi.org/technologies/digital-signature/certific...
I doubt that DarkMatter has any of this (not that this would reduce the risk but it could be used as an argument by Mozilla considering they're stuck between a rock and a hard place.
Rules exist for the purpose they serve, functions they allow to be easier and cheaper. Rules are not made so that rules have been made.
Those circumstances would easily fall under the purpose they serve.
It requires attention by the people applying the rules to recognize the facts, but paying attention is the reason to have people in the loop. Any machine can be corrupted.
Play stupid games, win stupid prizes.